The types and amount of plant raw materials which can be used as components in animal feeds will often be limited by the ability of the animals to digest them. Feed enhancing enzymes are enzymes, usually of microbial origin, that by improving feed digestibility are able to increase the efficiency of its utilization.
Xylanolytic enzymes (EC 3.2.1.8) are well known as feed enhancing enzymes. Xylanases obtained from strains of Bacillus, Aspergillus, Trichoderma, Acremonium have been reported. Moreover, an enzyme preparation obtained by submerged fermentation of Humicola insolens have been marketed (Bio-Feed™ Plus, available from Novo Nordisk A/S, Denmark).
Xylanase preparations obtained from strains of the fungus Thermomyces lanuginosus (Syn. Humicola lanuginosa) have been described [cf. Lischnig T, Purkarthofer H and Steiner W; Biotechnology Letters 1993 15 (4) 411–414; Gomes J, Purkarthofer H, Hayn M, Kapplmüller J, Sinner M, and Steiner W, Appl. Microbiol. Biotechnol. 1993 39 700–707]. However, the use of a Thermomyces lanuginosus xylanase as a feed enhancing enzyme has never been disclosed.
Moreover, the xylanase preparations described in the prior art all relates to complex enzyme preparations comprising multiple enzyme components. Monocomponent xylanase preparations derived from Thermomyces by use of recombinant DNA technology have never been disclosed.
For many applications, the use of complex enzyme preparations is considered beneficial due to a synergistic effect arising from the co-operative action of multiple components. For some applications, e.g. the conversion of lignocellulose into liquid feedstocks or fuel, the processing of foods, and in particular for increasing digestibility of animal feed, a mixture of xylanolytic and cellulytic enzymes is regarded having optimal performance [Alam M, Gomes I, Mohiuddin G, & Hoq M M; Enzyme Microb. Technol. 1994 16 298–302].